package memento;
public class MementoPattern
{
    public static void main(String[] args)
    {
        Originator or=new Originator();
        Caretaker cr=new Caretaker();
        or.setState("S0");
        System.out.println("初始状态:"+or.getState());
        cr.setMemento(or.createMemento()); //保存状态
        or.setState("S1");
        System.out.println("新的状态:"+or.getState());
        or.restoreMemento(cr.getMemento()); //恢复状态
        System.out.println("恢复状态:"+or.getState());
    }
}
//备忘录
class Memento
{
    private String state;
    public Memento(String state)
    {
        this.state=state;
    }
    public void setState(String state)
    {
        this.state=state;
    }
    public String getState()
    {
        return state;
    }
}
//发起人
class Originator
{
    private String state;
    public void setState(String state)
    {
        this.state=state;
    }
    public String getState()
    {
        return state;
    }
    public Memento createMemento()
    {
        return new Memento(state);
    }
    public void restoreMemento(Memento m)
    {
        this.setState(m.getState());
    }
}
//管理者
class Caretaker
{
    private Memento memento;
    public void setMemento(Memento m)
    {
        memento=m;
    }
    public Memento getMemento()
    {
        return memento;
    }
}
